1. Field of the Invention
The present invention relates to a high-impedance substrate, an antenna device and a mobile radio device, and relates to, for example, a technique for downsizing high-impedance substrates.
2. Related Art
As described in National Publication of International Patent Application No. 2004-535720, a conventional high-impedance substrate has a structure in which a large number of metal patches (metal plates) are periodically arranged. One conventional issue that can be surmounted by such a high-impedance substrate is the adoption of a low profile for an antenna on a conductor plate. National Publication of International Patent Application No. 2004-535720 utilizes its advantages to achieve a low-profile antenna on the rooftop of an automobile, thereby solving the conventional problems existing in vehicle-mounted antennas with respect to mechanical strength and aesthetic properties. However, since a large-area is assumed for mounting of such a conventional high-impedance substrate, mounting on a small-sized device is difficult. In particular, mounting a conventional high-impedance substrate on extremely small devices such as a mobile phone is difficult even if the substrate includes only two rows of metal patches.
As described above, a conventional high-impedance substrate has a problem in that mounting on a small-sized device is difficult.